1. Field of the Invention
The present invention relates to a writing apparatus and a writing method. For example, it relates to a writing apparatus which writes a pattern onto a target workpiece by using electron beams, and to a method thereof.
2. Description of Related Art
The microlithography technique which advances micro-miniaturization of semiconductor devices is extremely important as being the only process of forming patterns in semiconductor manufacturing processes. In recent years, with high integration of large-scale integrated circuits (LSI), a line width (critical dimension) required for semiconductor device circuits is shrinking year by year. In order to form a desired circuit pattern on such semiconductor devices, a master or “original” pattern (also called a mask or a reticle) of high precision is required. Then, the electron beam writing technique intrinsically having excellent resolution is used for producing such a highly precise master pattern.
FIG. 12 is a schematic diagram showing operations of a variable-shaped electron beam (EB) type writing apparatus. As shown in FIG. 12, the variable-shaped electron beam writing apparatus, including two aperture plates, operates as follows: A first aperture plate 410 has a quadrangular such as rectangular opening or “hole” 411 for shaping an electron beam 330. A second aperture plate 420 has a variable-shaped opening 421 for shaping the electron beam 330 that has passed through the opening 411 into a desired rectangular shape. The electron beam 330, emitted from a charged particle source 430 and having passed through the opening 411, is deflected by a deflector, to pass through a part of the variable-shaped opening 421 and thereby to irradiate a target workpiece or “sample” mounted on a stage which continuously moves in one predetermined direction (e.g. X direction) during writing or “drawing.” In other words, a rectangular shape formed as a result of passing through both the opening 411 and the variable-shaped opening 421 is written in the writing region of a target workpiece 340 on the stage. This method of forming a given shape by letting beams pass through both the opening 411 and the variable-shaped opening 421 is referred to as a variable shaped method.
On a mask serving as a target workpiece, an identification (ID) figure for identifying the mask itself is written in the outside of the chip region for manufacturing a semiconductor. For example, the identification figure is written as a barcode pattern (refer to, e.g., Japanese Patent Application Laid-open (JP-A) No. 2001-92110). As another example, there is disclosed that a pattern formed by encoding information which is for inspecting a photomask is formed on the photomask (refer to, e.g., Japanese Patent Application Laid-open (JP-A) No. 2007-233164). Conventionally, since such an ID figure and an encoded pattern are formed in advance by using CAD etc., it is impossible to write information, such as information of just before writing or an actual writing time and date. Furthermore, of course, it is also impossible to write information of after starting writing. However, when performing processing and a defect inspection after writing a mask, there may be needed mask substrate information and/or information of when writing the mask. Conventionally, such information is managed independently from the mask substrate, and stored in the database etc. However, there is a strong request from the user to write such information on the mask as much as possible.
Thus, as mentioned above, it is strongly requested to write information, such as mask substrate information and information of when writing a mask, onto the mask as much as possible. However, conventionally, since figure data indicating an ID figure needs to be separately created in an external device in advance as well as pattern data for manufacturing a semiconductor, etc., it has been difficult to incorporate information produced after then, such as information of just before writing and information of when writing.